A couple who were taking a Carnival Cruise in the South Pacific were discovered missing from the ship on Thursday, sparking a major air and marine search over a vast portion of ocean off the coast of Australia.

The couple, Paul Rossington, 30, and Kristen Schroder, 27, were found to be missing on Thursday morning when the cruise ship docked at Sydney's Circular Quay, according to reports.

A review of the ship's surveillance videos has revealed that the pair went overboard at about 8:50pm on Wednesday night, approximately 65 miles off the coast of Forester, a city just under 200 miles from Sydney. It is not known yet whether the incident was intentional or accidental, though police are investigating.

The Australian Maritime Safety Authority, who is coordinating the search and rescue mission for the missing couple have said that airplanes, helicopters and boats have been dispatched to search a 300-square-nautical-mile stretch of sea in an area north of Sydney.

"From the information that we have received, we believe it's been now well over 13-14 hours that those two people have been in the water," New South Wales State Police Superintendent Mark Hutchings told reporters. "But as far as I'm concerned, as the commander, we are searching for them in the hope that we will find them alive out to sea."

According to a spokesperson for Carnival Cruise Lines, initial reports show the couple went missing Wednesday nights although officials on-board the ship only became aware of the situation after docking Thursday morning in Sydney. Upon realization of what happened, the ship immediately initiated its standard missing persons procedures, including a full search of the vessel, as per protocol.

"We have naturally been concerned since we became aware that two passengers were missing from Carnival Spirit, and our thoughts are clearly with their families at this difficult time," Carnival said in a statement. "We are working closely with New South Wales Police and assisting them in their inquiries."

The couple were traveling with family and friends on a 10-day cruise through the South Pacific. Prior to disembarking at the end of the trip in Sydney on Thursday, the ship's last stop was Mare Island in New Caledonia, from which it departed on Monday.